3 files changed, 125 insertions, 3 deletions

diff --git a/lib/data.dart b/lib/data.dart
index 365f5bc..ca350e5 100644
--- a/lib/data.dart
+++ b/lib/data.dart
@@ -1,7 +1,12 @@
+import 'dart:io';
+import 'dart:async';
+
 import 'package:flutter/foundation.dart';
 import 'package:mqtt_client/mqtt_client.dart';
 import 'package:mqtt_client/mqtt_server_client.dart';
 
+import 'db.dart';
+
 const int brokerPort = 1883;
 const String topicPrefix = 'sia';
 
@@ -22,6 +27,8 @@ enum MachineEvent {
 }
 
 class AppState with ChangeNotifier {
+  final DB db = DB();
+
   static const Map<MachineState, Map<MachineEvent, MachineState>> machine = <MachineState, Map<MachineEvent, MachineState>> {
     MachineState.init: <MachineEvent, MachineState> {
       MachineEvent.connect: MachineState.disconnected,
@@ -46,9 +53,25 @@ class AppState with ChangeNotifier {
   Map<String, bool> contacts = <String, bool>{};
   late MqttServerClient _client;
 
+  late Directory supportDir;
   String fqdn = '';
 
-  AppState();
+  AppState() {
+    unawaited(loadPersistence());
+  }
+
+  Future<void> loadPersistence() async {
+    await db.connect();
+    String? dbFqdn = await db.getServerFqdn();
+    if (dbFqdn == null) return;
+    fqdn = dbFqdn;
+    notifyListeners();
+  }
+
+  void setFqdn(String value) {
+    fqdn = value;
+    unawaited(db.setServerFqdn(value));
+  }
 
   void process(MachineEvent event) {
     MachineState lastState = state;
@@ -103,7 +126,7 @@ class AppState with ChangeNotifier {
     _client.onAutoReconnected = _onAutoReconnected;
 
     try {
-      _client.connect();
+      unawaited(_client.connect());
     } catch (e) {
       _client.disconnect();
       return;
diff --git a/lib/db.dart b/lib/db.dart
new file mode 100644
index 0000000..0b2cf7a
--- /dev/null
+++ b/lib/db.dart
@@ -0,0 +1,90 @@
+import 'dart:io';
+import 'dart:async';
+
+import 'package:path_provider/path_provider.dart';
+import 'package:sqlite3/sqlite3.dart';
+import 'package:path/path.dart' as p;
+
+class DB {
+  final Completer<Database?> _dbCompleter = Completer<Database?>();
+  static const List<String> migrations = <String>[
+    '''
+PRAGMA user_version = 1;
+CREATE TABLE "key_value" (
+	"key"	TEXT NOT NULL UNIQUE,
+	"value"	TEXT,
+	PRIMARY KEY("key")
+);
+    ''',
+  ];
+
+  Future<void> connect() async {
+    String path = await _getDbPath();
+    Database candidate = sqlite3.open(path);
+
+    migrate(candidate);
+
+    _dbCompleter.complete(candidate);
+  }
+
+  void dispose() async {
+    if (_dbCompleter.isCompleted == false) {
+      return;
+    }
+    Database? db = await _dbCompleter.future;
+    if (db == null) return;
+    db.close();
+  }
+
+  static Future<String> _getDbPath() async {
+    Directory supportDir = await getApplicationSupportDirectory();
+    return p.join(supportDir.path, 'main.sqlite3');
+  }
+
+  static void migrate(Database db) {
+    for (int i=0; i<migrations.length; i++) {
+      int? userVersion = _getUserVersion(db);
+      if (userVersion == null) return;
+
+      if (i == userVersion) {
+        db.execute(migrations[i]);
+      }
+    }
+  }
+
+  static int? _getUserVersion(Database db) {
+    ResultSet result = db.select('PRAGMA user_version;');
+    if (result.length != 1) return null;
+    return result.first.values.first as int;
+  }
+
+  Future<String?> getServerFqdn() async {
+    Database? db = await _dbCompleter.future;
+    if (db == null) return null;
+
+    ResultSet result = db.select(
+      'SELECT value FROM key_value WHERE key = \'server_fqdn\';'
+    );
+    if (result.length != 1) return null;
+
+    return result[0]['value'];
+  }
+
+  Future<void> setServerFqdn(String value) async {
+    Database? db = await _dbCompleter.future;
+    if (db == null) return;
+
+    String? current = await getServerFqdn();
+    if (current == null) {
+      db.execute(
+        'INSERT INTO key_value (key, value) VALUES (\'server_fqdn\', ?);',
+        <Object?>[value],
+      );
+    } else {
+      db.execute(
+        'UPDATE key_value SET value = ? WHERE key = \'server_fqdn\';',
+        <Object?>[value],
+      );
+    }
+  }
+}
diff --git a/lib/ui.dart b/lib/ui.dart
index 9603562..3a98be9 100644
--- a/lib/ui.dart
+++ b/lib/ui.dart
@@ -41,8 +41,17 @@ class _ConnectionPageState extends State<ConnectionPage> {
     final AppState provider = context.read<AppState>();
     controller = TextEditingController(text: provider.fqdn);
 
+    provider.addListener(() {
+      if (controller.text != provider.fqdn) {
+        controller.text = provider.fqdn;
+        controller.selection = TextSelection.fromPosition(
+          TextPosition(offset: controller.text.length),
+        );
+      }
+    });
+
     controller.addListener(() {
-      provider.fqdn = controller.text;
+      provider.setFqdn(controller.text);
     });
   }